A four-year, national survey (2013-17) among practicing allergists regarding serious allergic reactions to allergen injections
Published online: February 15, 2019
Subcutaneous allergen injection immunotherapy (SCIT), also known as allergy shots, has been used to effectively treat nasal allergies, asthma, and stinging insect allergies for over 100 years. Very rarely, allergy injections can result in severe, life-threatening allergic reactions. Studies prior to 2002 reported 3-4 fatal allergic reactions per year. Practice guidelines were first developed in 2003 by the Allergist community to improve safety and minimize risk for severe systemic reactions or fatal anaphylaxis. More recently, regulatory bodies have raised concerns about a possible risk of bacterial infections from allergy shots, although there is no evidence to support any risk of infections.
In a recent article published in The Journal of Allergy and Clinical Immunology: In Practice, Epstein et al present updated information regarding the risk of severe and fatal reactions from allergy shots, and policies that physicians may put in place to minimize risks. The risk of infections from allergy shots is also evaluated. The study began in 2008, and was sponsored by the American Academy of Allergy, Asthma, and Immunology (AAAAI), and the American College of Allergy, Asthma, & Immunology (ACAAI). Relevant information from participating practicing allergists was gathered each year up to 2016 using an electronic online survey. In recent years, the survey focused on the length of observation time that patients remain in the office after receiving an allergy shot, how often reactions occur outside of the Allergist’s office, and if prescribing an epinephrine auto-injector to injection patients might lower the risk of severe allergic reactions that start after leaving the Allergist’s office.
Data were gathered on 54.4 million injection visits between 2008 and 2016. Two confirmed fatal allergic reactions from allergy shots were reported between 2008-2014 and an additional five were confirmed between 2015-2017. No infections occurred in 17.3 million injection visits for 1.9 million patients receiving injections from 2014 to 2016. Three-fourths of physician practices required a waiting time of 30 minutes or more after allergy shots. The majority of allergic reactions to allergy shots occurred within 30 minutes, with about 15% of reactions occurring after 30 minutes. None of these delayed reactions (after 30 minutes) resulted in fatalities. One fatality occurred in a child that left the office before the recommended waiting time and did not promptly receive epinephrine, which is the standard treatment for severe allergic reactions or anaphylaxis to allergy shots. Patients with severe delayed reactions rarely used prescribed epinephrine auto-injector devices (26% of such patients used them between 2014-2015; and 8% used them between 2015-2016). Prescribing an epinephrine auto-injector did not lower the risk of severe delayed reactions. Other fatal reactions described in the study were associated with known risk factors, such as uncontrolled asthma, and especially severe asthma, and delays in treatment with epinephrine.
The average number of fatal reactions from allergy shots has declined to less than one fatality per year (1 in 9.1 million injection visits), compared to 3-4 fatalities per year (1 in 2.5 million injection visits) prior to 2003. There was an unexplained slight increase in fatalities for 2015-2017 that needs to be further investigated in subsequent years. No infections from allergy shots have been found during two years of surveillance, indicating that the current method for preparing allergy shots in the United States maintains sterility and does not lead to infections. Efforts to minimize known risk factors for fatal reactions are still needed, including: making sure that asthma is controlled in patients receiving allergy shots, and that patients with reactions receive prompt treatment with epinephrine. Interventions are needed to improve patient adherence with epinephrine for delayed reactions.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.